What happens when lightning strikes an airplane?

Lightning is an extremely dangerous phenomenon that takes place on earth. About 100 lightning bolts strike the Earth’s surface every second which is about 8 million per day and 3 billion each year. These numbers may sound frightening for things on the ground, but are these numbers as dangerous for things in the air? Let’s find out.

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Lightning strikes behind a B-52H Stratofortress at Minot Air Force Base.
Picture Credit: Shine Wire
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Let’s make one thing clear, airplanes are designed to withstand harsh and dangerous conditions. Whether it is due to bad weather, stalls, or structural forces. Each aircraft undergoes thousands of hours of testing and is only declared fit to fly when it passes each test. In case of lightning strikes, airplanes are designed to take them. Normally, when an aircraft is struck by one mid-flight, only for safety concerns it undergoes an inspection after landing, but in most cases the aircraft is either unharmed or sustains only minor damage.

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What happens?

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The fuselage of the aircraft acts as an entrance and exit point for the lightning. Electrical charges are transmitted through the entry pint and leave via the exit point keeping the plane unharmed. It usually enters the plane via the wing tip or the nose and leaves via the tail. When lightning strikes an airplane, the lightning bolt rejoins itself to the fuselage at other locations while the airplane is in the electric “circuit” between the cloud regions of opposite polarity. The current will travel through the conductive exterior skin and structures of the aircraft and exit of the tail. The fuselage acts as a Faraday cage (a container that blocks electromagnetic fields). Energy and electric charge from the lightning bolt run around the outside of the vessel, protecting the interior from any voltage. It acts as a conductive path, just like when you wear shoes while dealing with electricity. The shoes act as a conductor which allows the charges to discharge via the conductive path and into the ground. Pilots occasionally report temporary flickering of lights or short-lived interference with instruments.

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Picture Credit: Boeing
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The final say

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The majority of the skin of an aircraft consists of aluminum which conducts electricity extremely well. Overall, airplanes receive a rigorous set of lightning certification tests to verify the safety of their designs but the concern remains over the fuel system. The smallest of sparks could have severe consequences. As in 1967, an aircraft crashed due to a lightning strike that sparked in the fuel tanks causing an explosion. However, since then, no major accident has ever taken place due to a lightning strike. Newer airplanes like the Boeing 787 and the Airbus A350 are made with a higher proportion of composite materials like carbon fibers, resulting in a reduced electrical conductivity of the fuselage and wings. The aim is to reduce the damage caused by lightning strikes rather than trying to avoid them. For the passengers, they merely feel anything apart from a bright flash and a noise. So, next time if you are flying through a thunderstorm, have this article in mind and enjoy your flight!

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Sources

https://www.scientificamerican.com/article/what-happens-when-lightni/

https://time.com/4910412/plane-struck-lightning-safety/#:~:text=For%20safety%20reasons%2C%20planes%20hit,or%20sustains%20only%20minor%20damage.&text=Lightning%20typically%20strikes%20a%20relatively,the%20tail%2C%20according%20to%20Hansman.

Cover Photo Credits: https://www.thermofisher.com/blog/metals/see-the-latest-technology-to-protect-aircraft-against-lightning-strikes-at-space-tech-expo/

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